The subject invention generally relates to the measurement of temperatures within a body, and more particularly to a system of temperature measurement by monitoring the correlations in thermally-generated energy from inside the body.
There are many situations in medical diagnosis and treatment, industrial processing, geophysical exploration, and other fields where it is desirable to measure the temperature inside a material body, but it is not practical to insert a probe beyond the surface of the body. In medical diagnosis, the usefulness of temperature measurement at the few places available for probe insertion is well established. In recent years, thermograms produced by infrared camera equipment and other surface temperature measurement have shown promise as a means of detecting breast cancer lesions. A technique which extends temperature measurement to all soft-tissue parts of the body would be a powerful new diagnostic tool.
In medical therapy, a non-invasive temperature monitoring technique would be useful in almost any procedure involving heating or cooling of the soft tissues of the body. For example, hyperthermia has been found to be a promising technique, either alone or in combination with other modalities, for the treatment of cancer. However, its effectiveness is very sensitive to the temperature which is reached, becoming more effective as one approaches 45.degree. C., but tissue necrosis becomes a serious problem if the temperature goes above 45.degree. C. Therefore, a non-invasive method of monitoring temperature profiles is important if hyperthermia is to have wider potential.
In industrial processing, a suitable temperature distribution inside a large, hot body is often important during the heat treatment and cooling process. For example, the casting of large thickness of glass and other brittle materials is costly, partly because of a high failure rate which might be alleviated by a non-invasive temperature monitoring system. Data needed for geophysical exploration and monitoring would be more readily obtained if non-invasive techniques could provide temperature profiles as a function of depth for distances of several meters into surface rocks or into the region around a bore hole.
One technique for non-invasive measurement of temperature is electromagnetic radiometry which is based on so-called black body radiation. This is electromagnetic energy inherently radiated by bodies having temperatures above 0.degree. K. Infrared frequencies have been detected to provide thermograms of the surfaces of bodies. In order to detect thermally generated energy below the surface of a body, longer wavelength microwave frequencies are detected. Another technique for non-invasive measurement of temperature is described in U.S. Pat. No. 4,246,784 to Theodore Bowen. This technique may be described as acoustic radiometry. While both of these techniques are useful for making non-invasive temperature measurements, what is actually measured in either case is an average temperature along the axis of the directivity pattern of the transducer or antenna used to receive the thermally-generated energy.